ACPI / sleep: Introduce acpi_os_prepare_extended_sleep() for extended sleep path

Like acpi_os_prepare_sleep(), register a callback for use in systems
like tboot, and xen, which have system specific requirements outside
of ACPICA.  This mirrors the functionality in acpi_os_prepare_sleep(),
called from acpi_hw_sleep()

Signed-off-by: Ben Guthro <benjamin.guthro@citrix.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/osl.c

@@ -79,6 +79,8 @@ extern char line_buf[80];
 
 static int (*__acpi_os_prepare_sleep)(u8 sleep_state, u32 pm1a_ctrl,
 				      u32 pm1b_ctrl);
+static int (*__acpi_os_prepare_extended_sleep)(u8 sleep_state, u32 val_a,
+				      u32 val_b);
 
 static acpi_osd_handler acpi_irq_handler;
 static void *acpi_irq_context;
@@ -1779,6 +1781,28 @@ void acpi_os_set_prepare_sleep(int (*func)(u8 sleep_state,
 	__acpi_os_prepare_sleep = func;
 }
 
+acpi_status acpi_os_prepare_extended_sleep(u8 sleep_state, u32 val_a,
+				  u32 val_b)
+{
+	int rc = 0;
+	if (__acpi_os_prepare_extended_sleep)
+		rc = __acpi_os_prepare_extended_sleep(sleep_state,
+					     val_a, val_b);
+	if (rc < 0)
+		return AE_ERROR;
+	else if (rc > 0)
+		return AE_CTRL_SKIP;
+
+	return AE_OK;
+}
+
+void acpi_os_set_prepare_extended_sleep(int (*func)(u8 sleep_state,
+			       u32 val_a, u32 val_b))
+{
+	__acpi_os_prepare_extended_sleep = func;
+}
+
+
 void alloc_acpi_hp_work(acpi_handle handle, u32 type, void *context,
 			void (*func)(struct work_struct *work))
 {